WO2007080901A1

WO2007080901A1 - Radio control device and transmission power control method

Info

Publication number: WO2007080901A1
Application number: PCT/JP2007/050186
Authority: WO
Inventors: Masafumi Usuda; Anil Umesh; Hidehiro Ando; Takuya Sato; Shinichi Sasaki; Kouji Makino
Original assignee: Ntt Docomo, Inc.
Priority date: 2006-01-10
Filing date: 2007-01-10
Publication date: 2007-07-19
Also published as: CN101371465B; US20100222094A1; KR101008299B1; EP1981180A1; EP1981180A4; KR20080089441A; US8041381B2; JP4761973B2; CN101371465A; JP2007184864A

Abstract

A radio control device (30) includes: a block error detection unit (31) for receiving a data block from a base station (20) and detecting a block error; and a target SIR calculation unit (32) for calculating a target SIR according to the detected block error ratio. The target SIR calculation unit (32) sets a first time interval shorter than a second time interval. The first time interval is from an error detection until reporting of the target SIR to the base station (20) when a block error is detected. The second time interval is from an error detection until reporting of the target SIR to the base station (20) when no block error is detected.

Description

Specification

Radio control apparatus and transmission power control method

Technical field

The present invention relates to a radio network controller and a transmission power control method.

Background art

[0002] In a CDMA mobile communication system, the transmission power control is performed with high accuracy, thereby increasing the capacity of the radio system by suppressing the interference given to other users as much as possible while maintaining the communication quality at a required level. be able to. In a CDMA mobile communication system, in order to make the received SIR (Signal to Interference power Ratio) close to the target SIR, the radio base station measures the received SIR, compares it with the target SIR, and transmits it. The inner loop transmission power control, which sends and indicates the power up and down to the mobile station as transmission power control bits, and the radio control device located at the upper level of the radio base station receive reception quality (for example, block error, block It has a two-stage configuration of outer loop transmission power control that measures the error rate) and instructs the radio base station about the target SIR in the radio base station so as to satisfy the target quality.

[0003] Ideally, the outer loop transmission power control should be performed every 1 [ΤΠ]. For example, block error is detected by CRC and the target SIR is updated every 1 [ΤΠ] as follows.

[0004] IF CRC check OK

Step— down = BLER—target * Step— size

R— target, n) = SIR— target, n-1)-Step— down

ELSE

Step— up = Step— size— BLER—target * ¾tep— size

SIR— target (n) = SIR— target (n— 1) + Step— up

However, if the target SIR is changed every TTI (Transport Time Interval), the control load of the radio control device increases. In addition, a large amount of interface bandwidth is consumed between the radio network controller and the radio base station. [0005] Therefore, instead of changing the target SIR for each kite, a method is provided in which a certain time interval is provided, and the target SIR is calculated for each time interval by the algorithm shown above and notified to the radio base station. Is also known.

However, when this method is used, the quality remains degraded during the above-described time interval due to the difference between the target quality and the set target SIR. What is striking is that when the network environment changes, such as before and after SHO (S oft Handover), the communication quality required by BLER (Block Error Rate) and the target SIR to be set change significantly. There is a case. At this time, there was a problem that the communication quality deteriorated greatly because the target SIR did not change during the time interval!

Disclosure of the invention

Therefore, in view of the above problems, the present invention prevents the radio quality from deteriorating when the line environment changes, and the load on the bandwidth between the radio controller and the radio base station while preventing the radio quality from deteriorating. It is an object of the present invention to provide a radio control apparatus and a transmission power control method that reduce the amount of noise.

[0008] A first feature of the present invention is that inner loop transmission power control is adopted between the mobile station and the radio base station, and outer loop transmission power control is adopted between the radio base station and the radio control device. Control of the radio base station instructing the mobile station to increase or decrease the transmission power by comparing the notified target SIR with the mobile station power and the received SIR of the received signal. A radio controller, (a) receiving a data block from a radio base station and measuring the reception quality; and (b) calculating a target SIR based on the reception quality measured by the measurement unit. (C) The target SIR calculation unit measures the reception quality when the reception quality deteriorates, and the first time interval until the target SIR is reported to the power radio base station If the reception quality does not deteriorate, The gist is that it is a radio control device that sets the power to be shorter than the second time interval until the target SIR is reported to the radio base station.

[0009] In the first aspect of the present invention, the measurement unit detects a block error from the received data block, and the target SIR calculation unit calculates a target SIR based on the detected block error rate. If a block error is detected, the error is detected and the power is sent to the radio base station. If the block error is not detected, set the first time interval until the notification of the error is shorter than the second time interval until error detection is performed and the target SIR is notified to the radio base station.

[0010] In addition, in the first feature of the present invention, when an error is detected, the target SIR calculation unit calculates a target SIR that increases by a predetermined ΔUP, and a predetermined time N [ΤΠ] Mistake

CNT

If not detected, the target SIR may be calculated by ΔDOWN by equation (1) using BLER—target as the target block error rate.

[Equation 2]

BLER— target

A DOWN = · A UP-NCNT …… Formula (1)

1 _ BLER— target

[0011] A second feature of the present invention is that inner loop transmission power control is adopted between the mobile station and the radio base station, and outer loop transmission power control is adopted between the radio base station and the radio control device. Compared with the radio controller that calculates the target SIR based on the received uplink channel quality, the target SIR notified from the radio controller and the received SIR of the signal received from the mobile station A transmission power control method in a communication system comprising a radio base station instructing a mobile station to increase or decrease transmission power by: (a) receiving and receiving data blocks from the radio base station Measuring the quality; (b) calculating a target SIR based on the measured reception quality; and (c) measuring the reception quality when the reception quality is reduced and then transmitting to the radio base station. Goal If the reception quality does not decrease, set the first time interval until the SIR notification is shorter than the second time interval until the target SIR is measured by measuring the reception quality. And a transmission power control method including the step of determining.

Brief Description of Drawings

FIG. 1 is a configuration block diagram of a communication system according to the present embodiment.

FIG. 2 is a configuration block diagram of a radio network controller and a base station according to the present embodiment.

FIG. 3 is a flowchart showing a transmission power control method according to the present embodiment. BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic.

[0014] (Configuration of communication system)

As shown in FIG. 1, the communication system according to the present embodiment includes a plurality of mobile stations 10a, 10b, 1

The base station 20 and the radio network controller 30 that manages the base station 20 are configured to be wirelessly connected to the Oc. In the present embodiment, the number of mobile stations that perform radio communication with the base station may be a number other than the force “3”, where the number is “3”.

[0015] In the communication system according to the present embodiment, inner loop transmission power control is adopted between the mobile stations 10a, 10b, 10c and the base station 20, and an outer loop is adopted between the base station 20 and the radio control apparatus 30. Transmit power control is adopted.

FIG. 2 shows an excerpt of the functions related to uplink transmission power control of the base station 20 and the radio network controller 30 according to the present embodiment.

[0017] The base station 20 includes a signal receiving unit 21, a RAKE receiving unit 22, an error correction decoding unit 23, and a reception S

IR calculation unit 24, target SIR storage unit 25, reception SIR comparison unit 26, TPC command transmission unit 2

And 7.

[0018] The signal receiving unit 21 converts the received signal of both the antenna power and the radio signal power into a baseband signal and transmits the baseband signal to the RAKE receiving unit 22.

[0019] The RAKE receiver 22 performs despreading and maximum ratio combining using a pilot signal to extract a desired user signal.

[0020] Reception SIR calculation unit 24 calculates a reception SIR using a signal of a pilot portion of a signal of a desired user.

[0021] The notified target SIR is compared with the received SIR. As a result of the comparison, if the received SIR is greater than the target SIR, a “Down” command is generated.

[0022] The TPC command transmitter 27 transmits a "Down" command or an "UP" command to the mobile station.

On the other hand, the signal that has undergone RAKE reception is input to error correction decoding section 23. Error correction recovery The code unit 23 performs error correction decoding. The signal after error correction decoding is transmitted to radio control apparatus 30.

Radio control apparatus 30 includes block error detection unit 31 and target SIR calculation unit 32, as shown in FIG.

The block error detection unit 31 (measurement unit) receives a data block from the base station 20 and measures the reception quality. For example, the block error detection unit 31 performs block error detection using CRC (Cyclic Redundancy Check).

[0026] The target SIR calculation unit 32 calculates a target SIR based on the reception quality measured by the block error detection unit 31 (measurement unit). For example, the target SIR calculation unit 32 calculates the target SIR based on the block error detected by the block error detection unit 31! /.

[0027] In addition, when the reception quality decreases, the target SIR calculation unit 32 measures the reception quality, and the reception quality decreases in the first time interval until the target SIR is notified to the base station 20 as well. In case of V, if the reception quality is measured, the power is set shorter than the second time interval until the target SIR is notified to the base station 20. For example, if the target SIR calculation unit 32 detects a block error, and does not detect the block error in the first time interval until error detection is performed and the target SIR is reported to the base station 20, The error is detected and the force is set shorter than the second time interval until the target SIR is notified to the base station 20.

[0028] Further, when an error is detected, the target SIR calculation unit 32 increases the target SIR by a predetermined step: ΔUP and immediately notifies the base station 20 of the increased target SIR. .

[0029] On the other hand, if no error is detected, only a predetermined time N [ΤΠ] is determined.

CNT

Wait and if no error is detected during NCNT [TTI], calculate the target SIR to be reduced by Δ DOWN according to equation (1).

[Equation 3]

BLER— target

A DOWN = · A UP-NCNT …… Formula (1)

1— BLER— target

[0030] Then, the target SIR calculation unit 32 notifies the base station 20 of the reduced target SIR.

[0031] (Transmission power control method)

Next, the transmission power control method according to the present embodiment will be described with reference to FIG. Fig 3 FIG. 5 is a flowchart showing the operation related to the outer loop of the wireless control device 30 in the present embodiment. Here, the case where the block error rate is used as the reception quality and the target SIR is calculated based on error detection will be described.

[0032] Here, tl and t2 are respectively a timer for determining the presence or absence of a CRC error, and a timing for notifying the base station of the target SIR lowered by ΔDOWN when no CRC error is detected. It is a timer and starts with tl = 0 and t2 = 0 at first.

[0033] The time intervals T1 and T2 are determined by the system as a cycle for determining a CRC error and a cycle for sending a "Down" command, respectively. T1 may determine the presence / absence of a frame CRC error as TTI, or may reduce the load as a number '[TTI]'. Also for T2, it is possible to increase the accuracy of transmission power control by frequently performing “Down” as a number '[TTI], and rarely perform “Down” as hundreds of [TTI]. As a result, the load on the RNC can be reduced as much as possible.

In FIG. 3, first, radio control apparatus 30 counts up timer (tl) until tl reaches T1 (Sll), and when tl reaches T1 (S10), CRC error occurs. Detection is performed (S12).

[0035] When an error is detected (S13), the radio network controller 30 determines a predetermined step.

Increase target SIR by Δ UP (S 14). Then, the increased target SIR is notified to the base station 20 (S20), and the process returns to the first process.

On the other hand, if no CRC error is detected (S13), radio control apparatus 30 resets timer (tl) (S15). Then, when t2 has not reached T2 (S16), the wireless control device 30 counts up the timer (t2) (S17) and returns to the first process.

On the other hand, when t2 reaches T2 (S16), radio control apparatus 30 decreases target SIR by A Down (S18) and resets timer (t2) (S19). Then, the lowered target SIR is notified to the base station 20 (S20), and the process returns to the first process.

[0038] (Function and effect)

According to the radio control device 30 and the transmission power control method according to the present embodiment, when the reception quality decreases, the first time interval from when the reception quality is measured until the target SIR is notified to the radio base station May be set shorter than the second time interval from when the reception quality is measured until the target SIR is reported to the radio base station, if the reception quality does not deteriorate. it can. In other words, when the reception quality decreases and the target SIR needs to be raised, the target SIR is notified as soon as possible, and when the target SIR needs to be lowered, the target SIR is set after a certain amount of time. By notifying, it is possible to reduce the control load of the wireless control device 30 and the bandwidth load between the wireless control device 30 and the base station 20 while preventing deterioration of the wireless quality when the line environment changes.

[0039] Also, in the present embodiment, when a block error rate is used as communication quality and a block error is detected, the first time until error detection is performed and the target SIR is reported to the radio base station is also possible. If no block error is detected, the interval can be set shorter than the second time interval from error detection until the target SIR is notified to the radio base station. By calculating the target SIR using the block error rate in this way, it is possible to detect radio quality degradation more accurately.

[0040] Also, when an error is detected, a target SIR that increases by a predetermined ΔUP is calculated, and when an NCNT [TTI] error is not detected for a predetermined time, the above equation (1) is used. It is preferable to calculate a target SIR that decreases by ΔDOWN.

[0041] (Other Embodiments)

The present invention is described by the above embodiments. It should not be understood that the description and drawings forming part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

For example, the block error detection unit 31 has been described as detecting a block error in order to measure the reception quality, but may detect a bit error in addition to a block error. In this case, the target SIR calculation unit 32 calculates the target SIR based on the detected bit error rate or the like.

[0043] Although the present invention has been described in detail using the above-described embodiments, it is understood by those skilled in the art that the present invention is not limited to the embodiments described in this specification. Is clear. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Accordingly, the description of the present specification is for illustrative purposes and does not have any restrictive meaning with respect to the present invention. Industrial applicability

As described above, according to the present invention, it is possible to reduce the control load of the wireless control device and the bandwidth load between the wireless control device and the wireless base station while preventing deterioration of the wireless quality when the line environment changes. A radio network controller and a transmission power control method can be provided.

Claims

The scope of the claims

[1] Inner loop transmission power control is adopted between the mobile station and the radio base station, and outer loop transmission power control is adopted between the radio base station and the radio control device, which is notified from the radio control device. The radio network controller that controls the radio base station that instructs the mobile station to increase or decrease the transmission power by comparing the received target SIR and the received SIR of the signal received from the mobile station Because

A measurement unit that receives a data block from the radio base station and measures reception quality; and a target SIR calculation unit that calculates a target SIR based on the reception quality measured by the measurement unit;

The target SIR calculation unit performs the first time interval until the target SIR is reported to the radio base station after the measurement of the reception quality when the reception quality is reduced. If not, the radio control apparatus is set shorter than a second time interval from when the reception quality is measured until the target SIR is notified to the radio base station.

[2] The measurement unit detects a block error from the received data block as the reception quality,

The target SIR calculation unit calculates the target SIR based on the detected block error rate. When the block error is detected, the target SIR calculation unit detects the block error and then transmits the target SIR to the radio base station. When the block error is not detected in the first time interval until the SIR is notified, the block error is detected and the target SIR is notified to the radio base station. The radio control apparatus according to claim 1, wherein the radio control apparatus is set shorter than the second time interval.

[3] If an error is detected, the target SIR calculation unit calculates a target SIR that increases by a predetermined ΔUP, and if no error is detected for a predetermined time N [ΤΠ], the BLER — T

CNT

3. The radio control apparatus according to claim 2, wherein a target SIR that is decreased by ΔDOWN is calculated by Equation (1) using arget as a target block error rate.

[Number 1] BLER_target

A DOWN = A UP-NCNT ...... Formula (1)

1 One BLER— target The inner loop transmission power control is adopted between the mobile station and the radio base station, and the outer loop transmission power control is adopted between the radio base station and the radio control device. By comparing the target SIR notified from the radio controller with the received SIR of the signal received from the mobile station, the target SIR is calculated based on the uplink channel quality received from A transmission power control method in a communication system including a radio base station that instructs the mobile station to increase or decrease transmission power,

Receiving a data block from the radio base station and measuring the reception quality; calculating a target SIR based on the measured reception quality; and receiving when the reception quality is reduced In the first time interval from when the quality measurement is performed until the target SIR is notified to the radio base station, when the reception quality does not deteriorate, the reception quality is measured and then the target SIR is sent to the radio base station. And a step of setting the time shorter than the second time interval until the notification of the transmission power.